Speedometer



March 9, 1937. R; Q HELGEBY 2,073,153

SPEEDOMETER Original Filed Deo. 23, l932 I 2 Sheets-Sheet 2 [/5 /Z Il Patented Mar. 9, 1937 UNITED STATES PATENT OFFICE SPEEDOMETER Ralph 0. Helgeby, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware 2 Claims.

This invention relates to measuring instruments and particularly to a combined Speed and distance recording instrument as used on vehicles.

A first object of the invention is to make such an instrument having the efficiency of instruments as heretofore manufactured by the use of a smaller number of parts and by the use of parts of smaller size.

Another object is to overcome manufacturing diiiculties by assembling the dial plate with the instrument instead of with the casing whereby calibration for accurate readings may be made before assembly of the instrument frame within the casing.

Another object is to improve the field plate by employing a cup having an uninterrupted annular wall and with no openings to receive tongues on the transfer pinion carriers. By this means 9 the eiiiciency of the field plate is considerably greater than would be the case if material were cut away from the wall to render visible characters on the underlying speed cup, or if slots be provided to locate the transfer pinion carrier.

Another object is an improvement relating to the spring regulator. By this improvement the regulator is conveniently snapped into its pivotal support whereby it has a frictional grip with the part to which it is pivoted whereby it is held in 30 adjusted position.

Other objects and advantages will be understood from the following description.

This application is a division of my application Serial Number 648,545 led December 23, 1932,

35 entitled speedometer, now abandoned.

In the drawings, Fig. 1 is a plan View looking at the dial which is broken away to show certain operating mechanism.

Fig. 2 is a section on line 2-2 of Fig. 1.

Fig. 3 is a section on line 3-3 of Fig. 1.

Fig. 4 is a section on line 4-4 of Fig. 2.

Fig. 5 is a section on line 5-5 of Fig. 2.

Fig. 6 is a perspective showing the frame, eld cup, jewel plate, and dial plate in disassembled relation.

Fig. '7 is a section corresponding to line 1 1 of Fig. l.

Referring by reference characters to the drawings, numeral 9 represents an improved die cast frame. This frame, as a result of the novel parts associated therewith, is of smaller size than frames heretofore used. In this. way economy in manufacture is effected. The frame is best illustrated in Fig. 6. It has a tubular shank projecting from a base |3 and is formed with side walls I5 and l1. A casing |9 is secured to the frame by fastening means 2| as shown in Fig. 2. The casing has a bezel 23 and a glass 25.

rIhe dial plate is shown at 21. Its mounting is unconventional in that it is secured by fastening means 29 to a jewel plate 3|, the latter extending from wall I5 to wall |1 and being secured to these walls by fastening means 33.

At its mid portion the jewel plate 3| hasan opening 35 to receive and hold the upper bearing 39 for the spindle 31. The spindle 31 carries a pointer 4| movable over the dial plate as usual. The lower bearings for the spindle are seen at 43 in the recess at the upper end of the rotor shaft 45. This shaft is rotatably mounted in the shank Il as usual and is to be driven by a suitable operating cable. A U-shaped magnet 41 with a temperature compensator 49 associated therewith is secured to the upper end of the rotor shaft 45, the end of the shaft being spun over for this purpose. A speed cup 5| is clamped as at 53 to the spindle 31, its lower wall surrounding the legs of the magnet as shown. Surrounding the speed cup 5| is the field cup 55. This cup is secured by tongues 51 through which and through threaded openings 59 in the frame are passed conventional fastening means 6|. The annular wall of the eld cup is unbroken whereby a more eiiicient intensification of the magnetic flux through the speed cup is insured than in those instruments where the field cup wall is cut away to render visible speed indicating gures on the speed cup enclosed within.

A tongue 63 is bent down` from the bottom of the field cup to engage an upward lug 65 on the speed cup to thereby limit the rotating movement of the latter under the influence of the spring 61. It will be understood that. the parts are so assembled that when the spring 61 holds the lug and tongue in contact, the pointer registers zero.

For Calibrating the spring 61 the following expedient is desired. A bridge part 69 is upwardly bent from the bottom of the field cup. Extending under the bridge and pivoted to the mid portion thereof is a lever 1|. To a lug 13 on the lever 1| is secured one end of a spring 61, the other end of which is made fast to the spindle. The ends of lever 1| rest on the bottom of the eld cup as shown. Rotation of the lever 1| obviously tensions the spring |51. The pivotal connection between the lever 1| and the bridge is made by providing a hole 40 in the bridge and extending therethrough an extruded lug 42 on the lever 1|, The curvature of the lever 1| is greater than that of the bridge, and when the lever is positioned with its ends resting on the bottom of the field cup the extruded lug snaps readily into the hole 48 and the friction between the bridge and the lever adjacent the hole 40 and the ends of lever 1| is suiiicient to hold the lever in its positions of adjustment.

The rotor shaft 45 has the additional function of driving the odometer mechanism as usual. The shaft is lubricated as it rotates within the shank by a saturated piece of felt or the like 15 held by a retainer or plug 11. The shaft 45 is held from inward movement by a collar 19 which with suitable clearance may engage a shoulder of the shank of the frame. It is held from outward movement by a retainer 8| held by the frame and located in a recess 83 of the shaft. Rotor shaft 45 is equipped with a worm 85 and for this reason is usually designated as the first worm shaft. Within the cast frame 9 (see Fig. 6) is a recess 81 with which the passage through the shank communicates. In this recess 81 is located a second worm shaft 89 (see Fig. 4) which has a worm 9| engaging worm 85 and a worm 93 at its other end. One reduced end of the second worm shaft 93 is received in an opening 99 in the frame, and the other end, also reduced, is received within a bushing 95 which is pressed into a frame opening 91. A third worm shaft 10| is positioned vertically as best shown in Fig. 5. Its ends are mounted in openings |93 in the frame and in the jewel plate 3|. This third worm shaft has a worm |01 engaging worm 93 and a Worm or gear element |99 at its other end.

'Ihe invention in the embodiment shown provides for two odometer wheel carrying shafts. Numeral represents the shaft of the season set of wheels ||3 (Fig. 1). Numeral |I5 is a shaft for the trip set of wheels ||1. Openings ||9 in the frame walls l5 and l1 support the ends of these shafts. Between the adjacent wheels of each set are transfer pinion carrier plates |2|. These plates are mounted on the shafts and ||5 respectively, and have radial extensions with notches as at |23. Secured to the bottom of the inverted iield cup are stamped anchor plates |25, the upstanding iianges of which engage the notches of the plates |2| as shown best by Fig. 3. By this means the plates |2| are held from rotation to maintain the transfer pinions in fixed position relative to the number wheels. Preferably the plates |25 are secured by extruding lugs |20 from the bottom of the field cup, which lugs enter and are secured in holes provided in the plates |25. By this means there are no slots needed to receive the tongues |23 and there is therefore no reduction of material in the field plate whereby its eii'iciency may be lessened.

The worm |09 of the third worm shaft engages on one side a driven form |29 on the axis of the season set of wheels for driving the wheels of that set, and also engages on its other side an idler pinion 3|, the axis of this pinion being mounted in a frame opening |33. By thus assembling the worm shaft a construction is provided rendering the frame and the shaft assembly adaptable for use with modified forms of odometer mechanism.

Pinion |3| normally (when the trip set is functioning) engages a pinion 35 which forms a part of a combined pinion and clutch element |31. This element is at all times in clutched engagement with the lowest denomination wheel of the trip set of wheels and is normally pressed to the right (Fig. 1) by a spring |49 to effect the engagement of the pinions |35 and |3I. In this way the trip set is operated simultaneously with the season set of wheels. To reset the trip set an axially movable stem |39 is manually operated. In being moved inward cam faces |4I and |43 on the reset stem and clutch element, respectively, function to move the pinion |35 away from pinion |3| and to engage pinion |35 with a pinion |45 on the reset stem. Thereafter rotation of the stem |39 operates through the pinions |45 and |35 to reset the trip set of wheels as desired. The reset stem may be held yieldably in either of its two positions of adjustment by a locking detent |41 (Fig. '7) which is projected by a flat spring |49 secured to the frame through an opening I5| and received in one or the other of two annular grooves |53 of the stem.

The instrument as thus described accomplishes the several objects enumerated in a way which will be obvious without further description.

I claim:

1. In combination, speed indicating mechanism including an indicating device having as a part thereof a spindle, an inverted cup-shaped field plate, spring means secured to said spindle to bias said device to Zero position, said cup having a continuous bridge extending diametrically above the bottom wall of said cup and integrally joining said bottom wall at its opposite ends, said bridge having a central opening, a spring regulator having an extruded portion rotatably supported in said opening and an arm attached to said spring,

2. The invention defined by claim 1, said regulator having its ends supported by the bottom of said cup and its intermediate pivoted portion sprung into the bridge opening whereby it is frictionally held in adjusted position.

RALPH O. HELGEBY. 

